Modelling of Close-Proximity Underwater Explosion Loads and Structural Response – Phase 2

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Authors
  1. Dunbar, T.E.
Corporate Authors
Defence R&D Canada - Atlantic, Dartmouth NS (CAN);MARTEC Ltd, Halifax NS (CAN)
Abstract
The response of square, thin, mild-steel plates to close proximity underwater explosion (UNDEX) loads was simulated using a coupled fluid-structure interaction approach. Three series of simulations (A, B, and C) were carried out, based on charge sizes and target geometries taken from experiments carried out at DRDC Suffield in 2007-08. Series A uses an 18 gauge target mild steel plate and a charge of 20g of C4 at standoff distances varying between 0.53R and 0.75R, where R is the maximum free field bubble radius. The critical standoff for rupture initiation was found to be between 0.69R and 0.75R. Series B used a 22 gauge target plate and a charge of 20g of C4 at standoff distances between 0.85 and 1.15R. The critical standoff range was found to be between 1.10R and 1.15R. Series C used an 18 gauge target plate and a charge of 50g of C4 at standoff distances varying between 1.06R and 1.25R. The critical standoff range was found to be between 1.06R and 1.15R. In all series, failure of the plate occurred by edge tearing that initiates at a mid-side edge and quickly progresses to the corner, where total failure occurs. For standoffs equal to or greater than 1.06R, the gas bubble is shown to expand without contacting the target plate, and collapses to a point in the water column above the plate. In contrast, at smaller standoff distances, the expanding gas bubbles contacts the target and collapses directly on to the target surface.

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Report Number
DRDC-ATLANTIC-CR-2009-180 — Contractor Report
Date of publication
01 Oct 2009
Number of Pages
84
DSTKIM No
CA034120
CANDIS No
533615
Format(s):
Electronic Document(PDF)

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